Jacks911

I spent some time under the car this winter after removing the engine pan, cleaning away dirt & oil smudge, and crumbling sound foam, etc. After all was done I have been looking at the slight oil seepage from the engine case and see that it is only fron 1 case nut. The stud threads are wet. It amounts to small drops growing to a 1 inch spot on the floor after a week. I can live with this - but wonder if these nuts have a seal or O-ring that can be replaced just by taking the nut off ? ? ? Can these nuts be torqued to stop a leak & if so to what spec? If it where a case reseal job it's not worth it. the only other seapage I see is from the chain covers and again very minor. With the pan on I never notice this.

Thanks is advance for any advice. <img src="confused.gif" border="0">

Kevin

Jack;

The main engine through bolts do have 2 orings per bolt. Do not tighten it. To replace the oring's the bolt will have to be removed, and re-installed.

horst

Kevin, is this a simple matter of removing the bolt (engine in) putting on some new "o" rings and re-torqueing?

Jeff Curtis

Jack, is the particular bolt in question a "case-thru" bolt or just one of the bolt/nut combination that runs along the "flange" of the case?

The difference between the two is that the cas-thru bolts are fairly long, running fairly close to the center of the case, basically supporting the upper and lower main bearing journals as to keep the crank in line and proper torque on the bearings...if it's one of these, you likely cannot get it out without disassembling most of the engine as the heads and cam housings are in the way...again, the bolts are fairly long.

I would assume you are referring to one of the "flange bolts", most are actually studs, mounted on one half of the case, with a nylok nut securing the other half to it. these run along the top and bottom seam of the engine case, with a few scattered sporatically down the rear, underneath the flywheel.

I would seriously doubt you have an engine case leak, unless it has been apart before...then I would only consider it a possibility. Your oil is likely running down from another source, the drops tend to "hangout" on the studs/nuts along the bottom of the case.

Just check it out again, oil leaks can be a bi#%$, as I know, I'm still chasing down a fairly messy one...think I may have located it today!

It's the 36mm fitting on the steel "L" shaped oil line that enters the engine case right underneath where the factory used to install engine mounted oil coolers on the 3.2 and below. It was relatively loose, I suspect it was seeping oil and it got everywhere!

As you may recall, I pulled my engine/trans. in January, with the hopes of tracking it down...after replacing several gaskets/seals/"O"-rings, I was VERY disappointed to discover that I didn't NAIL the leak! <img src="graemlins/cussing.gif" border="0" alt="[grrrrrrr]" />

Jacks911

Jeff,

As you said ...
"I would assume you are referring to one of the "flange bolts", most are actually studs, mounted on one half of the case, with a nylok nut securing the other half to it. these run along the top and bottom seam of the engine case, with a few scattered sporatically down the rear, underneath the flywheel."
The one that seeps is a stud almost dead center in the case. I cleaned all the surfaces around there absolutely dry. In fact the rest of the case was dry, no seepage from the heads or tubes of valve covers. After a drive, the stud end and nut where oily but nothing else was? left in the garage after a week and checked again, and drops had formed on the bottom of the flange, but the only oily surface appears to be the nut & stud? I must admit that when I first discovered this I did check these nuts with a wench and this one was easy to move with light hand torque. I did not apply any heavy pressure to the nut and it tightened about a 1/4 turn before stopping.

I believe these nuts take 25 lb/ft torque??? Is there an O-ring and special washer under the nut? Or... is this sealed Inside the case?

From the look of the engine I would say it has never been out - it is a post head gasket '91 - and has only 38,000 miles on it.

Thanks again for advice ....

Jeff Curtis

Okay, from your description, I still cannot discern if you are speaking of a case-thru bolt (long) or a flange bolt (maybe 1.5")??

Is the stud located on the seam of the case? If so, there are no "O"-rings, just Loctite sealant in between the flanges that basically "glues" the engine halves together, allow me to use that analogy as the Loctite that is widely used is not flexible...it's like hard candy when cured.

There is however, a Dow Corning RTV sealant that is becoming popular for both motorcycle and Porsche, etc. engine rebuilds...it cost about 3x of what the Loctite product does though. It is flexible and gets good reviews.

I'm sorry, if you truly have a leak at the flange of your engine case halves...it's NOT an easy fix, as the only way it can be cured it disassembling the case halves and resealing.

If it is a case-thru bolt, you could replace the "O"-ring on the nut side fairly easily...but the bolt side will be difficult as I mentioned earlier.

john walkers workshop

case thru bolt o rings can only be replaced after the cylinders are off. there's no room to work with them on. you're looking at a 30+ hour job, professionally, and 60+ hours at home in the garage. it better be a worthwhile leak.

Robert Coats

[quote]Originally posted by Jeff Curtis:
<strong>
It's the 36mm fitting on the steel "L" shaped oil line that enters the engine case right underneath where the factory used to install engine mounted oil coolers on the 3.2 and below. It was relatively loose, I suspect it was seeping oil and it got everywhere!</strong><hr></blockquote>

Got any photos or parts illustrations you can share with the fitting/location? I've got a very tiny weep I'd like to least attempt to correct, but other than cleaning and looking for fresh drops, I don't know where to starting looking. My leak is on the right side too...

Jeff Curtis

Robert, I've spent the last two days prepping my car for a three day track event...track tires are already on. So, when I change back to street tires on Monday, I'll get a good shot for you, but for now, the tires are staying on!

After about 50 miles of driving around for the last couple of days, yes, on track tires...I still can't decide if I've slowed down the leak, I hope I did or I'm gonna go nuts! <img src="graemlins/c.gif" border="0" alt="[ouch]" />

Jacks911

Jeff, (and others)

Thanks for the feedback. The leak is on one of the Flange Studs as you described it - about 1.5 inches long. Since the seepage is minor, I will live with it. One last thought/question - was I correct that the nut torque for these 10 mm studs is 25 lb/ft? I found this in Anderson's "Performance Handbook". I would like to verify this and assume if I check the lower nuts it should be done cold?

Thanks again, <img src="graemlins/wave.gif" border="0" alt="[byebye]" />

Jeff Curtis

Off the top of my head, 25lbs sounds correct...I use Bruce Anderson's book as well - so if it said 25lbs, I'd use 25lbs.

Sorry we can't help any further...I doubt the leak will get much worse.

GeoT3

Jack, I had a same problem with a leak by one of the flange nylok nuts but it was on or near the cam housing. The dealer, who discovered this leak, wanted to tear down the engine to RR. the bill was something like $2000.00. I said no way.

This was what I found. The nylok would just turn and turn with the stud - dealer though it was striped casing threads. I took the nylok and stud off the flang/engine case and separated the nut and stud. Examined the stud and found no loose case threads on the stud... proceeded to install the stud into the case until it was slight snug. I then istalled the nylok and carefully watching the stud (making sure it was not spining) until the nut was tight. This was 2 years ago and no leaks - thank God!

give this a try, cannot hurt!

christian

Has anybody made experiences with just using a very good SAE 30 oil (like Castrol GTX or Chevron RPM-Delo)? Most engine oils other than synthtic oils (Mobil 1 is very good) are basically SAE 5 or 10 with additives to cover a larger range and therefore not the best for engines. Only disadvantage is that you can only use it from 5 degree celsius outside temperature and up. I am pretty sure it would reduce engine leaks quite a bit and extend engine life as well. There is also a new additive I have heard about called Lucas heave duty oil stabilzer which is 100 % petroleum based and claims to reduce oil leaks - any experience?

Cupcar

Hope nobody is tightening the 8mm bolts around the crankcase-the ones with the 13mm across the flat nylock nuts-to 25 lb-ft. The spec is 17 lb-ft, you may strip at 25 lb-ft. <img src="graemlins/nono.gif" border="0" alt="[nono]" />